source3/smbd/fileio.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    read/write to a files_struct
   5    Copyright (C) Andrew Tridgell 1992-1998
   6    Copyright (C) Jeremy Allison 2000-2002. - write cache.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "smbd/globals.h"
  24
  25 static bool setup_write_cache(files_struct *, SMB_OFF_T);
  26
  27 /****************************************************************************
  28  Read from write cache if we can.
  29 ****************************************************************************/
  30
  31 static bool read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  32 {
  33         write_cache *wcp = fsp->wcp;
  34
  35         if(!wcp) {
  36                 return False;
  37         }
  38
  39         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
  40                 return False;
  41         }
  42
  43         memcpy(data, wcp->data + (pos - wcp->offset), n);
  44
  45         DO_PROFILE_INC(writecache_read_hits);
  46
  47         return True;
  48 }
  49
  50 /****************************************************************************
  51  Read from a file.
  52 ****************************************************************************/
  53
  54 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  55 {
  56         ssize_t ret=0,readret;
  57
  58         /* you can't read from print files */
  59         if (fsp->print_file) {
  60                 return -1;
  61         }
  62
  63         /*
  64          * Serve from write cache if we can.
  65          */
  66
  67         if(read_from_write_cache(fsp, data, pos, n)) {
  68                 fsp->fh->pos = pos + n;
  69                 fsp->fh->position_information = fsp->fh->pos;
  70                 return n;
  71         }
  72
  73         flush_write_cache(fsp, READ_FLUSH);
  74
  75         fsp->fh->pos = pos;
  76
  77         if (n > 0) {
  78 #ifdef DMF_FIX
  79                 int numretries = 3;
  80 tryagain:
  81                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  82
  83                 if (readret == -1) {
  84                         if ((errno == EAGAIN) && numretries) {
  85                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
  86                                 (void)sleep(10);
  87                                 --numretries;
  88                                 goto tryagain;
  89                         }
  90                         return -1;
  91                 }
  92 #else /* NO DMF fix. */
  93                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  94
  95                 if (readret == -1) {
  96                         return -1;
  97                 }
  98 #endif
  99                 if (readret > 0) {
 100                         ret += readret;
 101                 }
 102         }
 103
 104         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
 105                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 106
 107         fsp->fh->pos += ret;
 108         fsp->fh->position_information = fsp->fh->pos;
 109
 110         return(ret);
 111 }
 112
 113 /****************************************************************************
 114  *Really* write to a file.
 115 ****************************************************************************/
 116
 117 static ssize_t real_write_file(struct smb_request *req,
 118                                 files_struct *fsp,
 119                                 const char *data,
 120                                 SMB_OFF_T pos,
 121                                 size_t n)
 122 {
 123         ssize_t ret;
 124
 125         if (pos == -1) {
 126                 ret = vfs_write_data(req, fsp, data, n);
 127         } else {
 128                 fsp->fh->pos = pos;
 129                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
 130                         if (vfs_fill_sparse(fsp, pos) == -1) {
 131                                 return -1;
 132                         }
 133                 }
 134                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
 135         }
 136
 137         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 138                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 139
 140         if (ret != -1) {
 141                 fsp->fh->pos += ret;
 142
 143 /* Yes - this is correct - writes don't update this. JRA. */
 144 /* Found by Samba4 tests. */
 145 #if 0
 146                 fsp->position_information = fsp->pos;
 147 #endif
 148         }
 149
 150         return ret;
 151 }
 152
 153 /****************************************************************************
 154  File size cache change.
 155  Updates size on disk but doesn't flush the cache.
 156 ****************************************************************************/
 157
 158 static int wcp_file_size_change(files_struct *fsp)
 159 {
 160         int ret;
 161         write_cache *wcp = fsp->wcp;
 162
 163         wcp->file_size = wcp->offset + wcp->data_size;
 164         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 165         if (ret == -1) {
 166                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
 167                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
 168         }
 169         return ret;
 170 }
 171
 172 static void update_write_time_handler(struct event_context *ctx,
 173                                       struct timed_event *te,
 174                                       struct timeval now,
 175                                       void *private_data)
 176 {
 177         files_struct *fsp = (files_struct *)private_data;
 178
 179         /* Remove the timed event handler. */
 180         TALLOC_FREE(fsp->update_write_time_event);
 181         DEBUG(5, ("Update write time on %s\n", fsp->fsp_name));
 182
 183         /* change the write time if not already changed by someone else */
 184         update_write_time(fsp);
 185 }
 186
 187 /*********************************************************
 188  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
 189  in the future.
 190 *********************************************************/
 191
 192 void trigger_write_time_update(struct files_struct *fsp)
 193 {
 194         int delay;
 195
 196         if (fsp->write_time_forced) {
 197                 /* No point - "sticky" write times
 198                  * in effect.
 199                  */
 200                 return;
 201         }
 202
 203         if (fsp->update_write_time_triggered) {
 204                 /*
 205                  * We only update the write time
 206                  * on the first write. After that
 207                  * no other writes affect this.
 208                  */
 209                 return;
 210         }
 211         fsp->update_write_time_triggered = true;
 212
 213         delay = lp_parm_int(SNUM(fsp->conn),
 214                             "smbd", "writetimeupdatedelay",
 215                             WRITE_TIME_UPDATE_USEC_DELAY);
 216
 217         /* trigger the update 2 seconds later */
 218         fsp->update_write_time_on_close = true;
 219         fsp->update_write_time_event =
 220                 event_add_timed(smbd_event_context(), NULL,
 221                                 timeval_current_ofs(0, delay),
 222                                 update_write_time_handler, fsp);
 223 }
 224
 225 void trigger_write_time_update_immediate(struct files_struct *fsp)
 226 {
 227         if (fsp->write_time_forced) {
 228                 /*
 229                  * No point - "sticky" write times
 230                  * in effect.
 231                  */
 232                 return;
 233         }
 234
 235         TALLOC_FREE(fsp->update_write_time_event);
 236         DEBUG(5, ("Update write time immediate on %s\n", fsp->fsp_name));
 237
 238         fsp->update_write_time_triggered = true;
 239
 240         fsp->update_write_time_on_close = false;
 241         update_write_time(fsp);
 242 }
 243
 244 /****************************************************************************
 245  Write to a file.
 246 ****************************************************************************/
 247
 248 ssize_t write_file(struct smb_request *req,
 249                         files_struct *fsp,
 250                         const char *data,
 251                         SMB_OFF_T pos,
 252                         size_t n)
 253 {
 254         write_cache *wcp = fsp->wcp;
 255         ssize_t total_written = 0;
 256         int write_path = -1;
 257
 258         if (fsp->print_file) {
 259                 fstring sharename;
 260                 uint32 jobid;
 261
 262                 if (!rap_to_pjobid(fsp->rap_print_jobid, sharename, &jobid)) {
 263                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 264                                                 (unsigned int)fsp->rap_print_jobid ));
 265                         errno = EBADF;
 266                         return -1;
 267                 }
 268
 269                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 270         }
 271
 272         if (!fsp->can_write) {
 273                 errno = EPERM;
 274                 return -1;
 275         }
 276
 277         if (!fsp->modified) {
 278                 SMB_STRUCT_STAT st;
 279                 fsp->modified = True;
 280
 281                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
 282                         int dosmode;
 283                         trigger_write_time_update(fsp);
 284                         dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 285                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 286                                         MAP_ARCHIVE(fsp->conn)) &&
 287                                         !IS_DOS_ARCHIVE(dosmode)) {
 288                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
 289                                                 dosmode | aARCH,&st,
 290                                                 NULL,
 291                                                 false);
 292                         }
 293
 294                         /*
 295                          * If this is the first write and we have an exclusive oplock then setup
 296                          * the write cache.
 297                          */
 298
 299                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 300                                 setup_write_cache(fsp, st.st_size);
 301                                 wcp = fsp->wcp;
 302                         }
 303                 }
 304         }
 305
 306 #ifdef WITH_PROFILE
 307         DO_PROFILE_INC(writecache_total_writes);
 308         if (!fsp->oplock_type) {
 309                 DO_PROFILE_INC(writecache_non_oplock_writes);
 310         }
 311 #endif
 312
 313         /*
 314          * If this file is level II oplocked then we need
 315          * to grab the shared memory lock and inform all
 316          * other files with a level II lock that they need
 317          * to flush their read caches. We keep the lock over
 318          * the shared memory area whilst doing this.
 319          */
 320
 321         release_level_2_oplocks_on_change(fsp);
 322
 323 #ifdef WITH_PROFILE
 324         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 325                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 326 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 327                         profile_p->writecache_init_writes,
 328                         profile_p->writecache_abutted_writes,
 329                         profile_p->writecache_total_writes,
 330                         profile_p->writecache_non_oplock_writes,
 331                         profile_p->writecache_allocated_write_caches,
 332                         profile_p->writecache_num_write_caches,
 333                         profile_p->writecache_direct_writes,
 334                         profile_p->writecache_num_perfect_writes,
 335                         profile_p->writecache_read_hits ));
 336
 337                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 338                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 339                         profile_p->writecache_flushed_writes[READ_FLUSH],
 340                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 341                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 342                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 343                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 344                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 345         }
 346 #endif
 347
 348         if (wcp && req->unread_bytes) {
 349                 /* If we're using receivefile don't
 350                  * deal with a write cache.
 351                  */
 352                 flush_write_cache(fsp, WRITE_FLUSH);
 353                 delete_write_cache(fsp);
 354                 wcp = NULL;
 355         }
 356
 357         if(!wcp) {
 358                 DO_PROFILE_INC(writecache_direct_writes);
 359                 total_written = real_write_file(req, fsp, data, pos, n);
 360                 return total_written;
 361         }
 362
 363         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 364                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 365
 366         fsp->fh->pos = pos + n;
 367
 368         /*
 369          * If we have active cache and it isn't contiguous then we flush.
 370          * NOTE: There is a small problem with running out of disk ....
 371          */
 372
 373         if (wcp->data_size) {
 374                 bool cache_flush_needed = False;
 375
 376                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 377
 378                         /* ASCII art.... JRA.
 379
 380       +--------------+-----
 381       | Cached data  | Rest of allocated cache buffer....
 382       +--------------+-----
 383
 384             +-------------------+
 385             | Data to write     |
 386             +-------------------+
 387
 388                         */
 389
 390                         /*
 391                          * Start of write overlaps or abutts the existing data.
 392                          */
 393
 394                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 395
 396                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 397
 398                         /*
 399                          * Update the current buffer size with the new data.
 400                          */
 401
 402                         if(pos + data_used > wcp->offset + wcp->data_size) {
 403                                 wcp->data_size = pos + data_used - wcp->offset;
 404                         }
 405
 406                         /*
 407                          * Update the file size if changed.
 408                          */
 409
 410                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 411                                 if (wcp_file_size_change(fsp) == -1) {
 412                                         return -1;
 413                                 }
 414                         }
 415
 416                         /*
 417                          * If we used all the data then
 418                          * return here.
 419                          */
 420
 421                         if(n == data_used) {
 422                                 return n;
 423                         } else {
 424                                 cache_flush_needed = True;
 425                         }
 426                         /*
 427                          * Move the start of data forward by the amount used,
 428                          * cut down the amount left by the same amount.
 429                          */
 430
 431                         data += data_used;
 432                         pos += data_used;
 433                         n -= data_used;
 434
 435                         DO_PROFILE_INC(writecache_abutted_writes);
 436                         total_written = data_used;
 437
 438                         write_path = 1;
 439
 440                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 441                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 442
 443                         /* ASCII art.... JRA.
 444
 445                         +---------------+
 446                         | Cache buffer  |
 447                         +---------------+
 448
 449             +-------------------+
 450             | Data to write     |
 451             +-------------------+
 452
 453                         */
 454
 455                         /*
 456                          * End of write overlaps the existing data.
 457                          */
 458
 459                         size_t data_used = pos + n - wcp->offset;
 460
 461                         memcpy(wcp->data, data + n - data_used, data_used);
 462
 463                         /*
 464                          * Update the current buffer size with the new data.
 465                          */
 466
 467                         if(pos + n > wcp->offset + wcp->data_size) {
 468                                 wcp->data_size = pos + n - wcp->offset;
 469                         }
 470
 471                         /*
 472                          * Update the file size if changed.
 473                          */
 474
 475                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 476                                 if (wcp_file_size_change(fsp) == -1) {
 477                                         return -1;
 478                                 }
 479                         }
 480
 481                         /*
 482                          * We don't need to move the start of data, but we
 483                          * cut down the amount left by the amount used.
 484                          */
 485
 486                         n -= data_used;
 487
 488                         /*
 489                          * We cannot have used all the data here.
 490                          */
 491
 492                         cache_flush_needed = True;
 493
 494                         DO_PROFILE_INC(writecache_abutted_writes);
 495                         total_written = data_used;
 496
 497                         write_path = 2;
 498
 499                 } else if ( (pos >= wcp->file_size) &&
 500                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 501                                         (pos > wcp->offset + wcp->data_size) &&
 502                                         (pos < wcp->offset + wcp->alloc_size) ) {
 503
 504                         /* ASCII art.... JRA.
 505
 506                        End of file ---->|
 507
 508                         +---------------+---------------+
 509                         | Cached data   | Cache buffer  |
 510                         +---------------+---------------+
 511
 512                                               +-------------------+
 513                                               | Data to write     |
 514                                               +-------------------+
 515
 516                         */
 517
 518                         /*
 519                          * Non-contiguous write part of which fits within
 520                          * the cache buffer and is extending the file
 521                          * and the cache contents reflect the current
 522                          * data up to the current end of the file.
 523                          */
 524
 525                         size_t data_used;
 526
 527                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 528                                 data_used = n;
 529                         } else {
 530                                 data_used = wcp->offset + wcp->alloc_size - pos;
 531                         }
 532
 533                         /*
 534                          * Fill in the non-continuous area with zeros.
 535                          */
 536
 537                         memset(wcp->data + wcp->data_size, '\0',
 538                                 pos - (wcp->offset + wcp->data_size) );
 539
 540                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 541
 542                         /*
 543                          * Update the current buffer size with the new data.
 544                          */
 545
 546                         if(pos + data_used > wcp->offset + wcp->data_size) {
 547                                 wcp->data_size = pos + data_used - wcp->offset;
 548                         }
 549
 550                         /*
 551                          * Update the file size if changed.
 552                          */
 553
 554                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 555                                 if (wcp_file_size_change(fsp) == -1) {
 556                                         return -1;
 557                                 }
 558                         }
 559
 560                         /*
 561                          * If we used all the data then
 562                          * return here.
 563                          */
 564
 565                         if(n == data_used) {
 566                                 return n;
 567                         } else {
 568                                 cache_flush_needed = True;
 569                         }
 570
 571                         /*
 572                          * Move the start of data forward by the amount used,
 573                          * cut down the amount left by the same amount.
 574                          */
 575
 576                         data += data_used;
 577                         pos += data_used;
 578                         n -= data_used;
 579
 580                         DO_PROFILE_INC(writecache_abutted_writes);
 581                         total_written = data_used;
 582
 583                         write_path = 3;
 584
 585                 } else if ( (pos >= wcp->file_size) &&
 586                             (n == 1) &&
 587                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 588                             (pos < wcp->file_size + wcp->alloc_size)) {
 589
 590                         /*
 591
 592                 End of file ---->|
 593
 594                  +---------------+---------------+
 595                  | Cached data   | Cache buffer  |
 596                  +---------------+---------------+
 597
 598                                  |<------- allocated size ---------------->|
 599
 600                                                          +--------+
 601                                                          | 1 Byte |
 602                                                          +--------+
 603
 604                         MS-Office seems to do this a lot to determine if there's enough
 605                         space on the filesystem to write a new file.
 606
 607                         Change to :
 608
 609                 End of file ---->|
 610                                  +-----------------------+--------+
 611                                  | Zeroed Cached data    | 1 Byte |
 612                                  +-----------------------+--------+
 613                         */
 614
 615                         flush_write_cache(fsp, WRITE_FLUSH);
 616                         wcp->offset = wcp->file_size;
 617                         wcp->data_size = pos - wcp->file_size + 1;
 618                         memset(wcp->data, '\0', wcp->data_size);
 619                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 620
 621                         /*
 622                          * Update the file size if changed.
 623                          */
 624
 625                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 626                                 if (wcp_file_size_change(fsp) == -1) {
 627                                         return -1;
 628                                 }
 629                         }
 630
 631                         return n;
 632
 633                 } else {
 634
 635                         /* ASCII art..... JRA.
 636
 637    Case 1).
 638
 639                         +---------------+---------------+
 640                         | Cached data   | Cache buffer  |
 641                         +---------------+---------------+
 642
 643                                                               +-------------------+
 644                                                               | Data to write     |
 645                                                               +-------------------+
 646
 647    Case 2).
 648
 649                            +---------------+---------------+
 650                            | Cached data   | Cache buffer  |
 651                            +---------------+---------------+
 652
 653    +-------------------+
 654    | Data to write     |
 655    +-------------------+
 656
 657     Case 3).
 658
 659                            +---------------+---------------+
 660                            | Cached data   | Cache buffer  |
 661                            +---------------+---------------+
 662
 663                   +-----------------------------------------------------+
 664                   | Data to write                                       |
 665                   +-----------------------------------------------------+
 666
 667                   */
 668
 669                         /*
 670                          * Write is bigger than buffer, or there is no overlap on the
 671                          * low or high ends.
 672                          */
 673
 674                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 675 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 676
 677                         /*
 678                          * If write would fit in the cache, and is larger than
 679                          * the data already in the cache, flush the cache and
 680                          * preferentially copy the data new data into it. Otherwise
 681                          * just write the data directly.
 682                          */
 683
 684                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 685                                 cache_flush_needed = True;
 686                         } else {
 687                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 688
 689                                 /*
 690                                  * If the write overlaps the entire cache, then
 691                                  * discard the current contents of the cache.
 692                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 693                                  */
 694
 695                                 if ((pos <= wcp->offset) &&
 696                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 697                                         DEBUG(9,("write_file: discarding overwritten write \
 698 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 699                                         wcp->data_size = 0;
 700                                 }
 701
 702                                 DO_PROFILE_INC(writecache_direct_writes);
 703                                 if (ret == -1) {
 704                                         return ret;
 705                                 }
 706
 707                                 if (pos + ret > wcp->file_size) {
 708                                         wcp->file_size = pos + ret;
 709                                 }
 710
 711                                 return ret;
 712                         }
 713
 714                         write_path = 4;
 715
 716                 }
 717
 718                 if (cache_flush_needed) {
 719                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 720 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 721                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 722                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 723
 724                         flush_write_cache(fsp, WRITE_FLUSH);
 725                 }
 726         }
 727
 728         /*
 729          * If the write request is bigger than the cache
 730          * size, write it all out.
 731          */
 732
 733         if (n > wcp->alloc_size ) {
 734                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 735                 if (ret == -1) {
 736                         return -1;
 737                 }
 738
 739                 if (pos + ret > wcp->file_size) {
 740                         wcp->file_size = pos + n;
 741                 }
 742
 743                 DO_PROFILE_INC(writecache_direct_writes);
 744                 return total_written + n;
 745         }
 746
 747         /*
 748          * If there's any data left, cache it.
 749          */
 750
 751         if (n) {
 752 #ifdef WITH_PROFILE
 753                 if (wcp->data_size) {
 754                         DO_PROFILE_INC(writecache_abutted_writes);
 755                 } else {
 756                         DO_PROFILE_INC(writecache_init_writes);
 757                 }
 758 #endif
 759                 memcpy(wcp->data+wcp->data_size, data, n);
 760                 if (wcp->data_size == 0) {
 761                         wcp->offset = pos;
 762                         DO_PROFILE_INC(writecache_num_write_caches);
 763                 }
 764                 wcp->data_size += n;
 765
 766                 /*
 767                  * Update the file size if changed.
 768                  */
 769
 770                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 771                         if (wcp_file_size_change(fsp) == -1) {
 772                                 return -1;
 773                         }
 774                 }
 775                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 776                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 777
 778                 total_written += n;
 779                 return total_written; /* .... that's a write :) */
 780         }
 781
 782         return total_written;
 783 }
 784
 785 /****************************************************************************
 786  Delete the write cache structure.
 787 ****************************************************************************/
 788
 789 void delete_write_cache(files_struct *fsp)
 790 {
 791         write_cache *wcp;
 792
 793         if(!fsp) {
 794                 return;
 795         }
 796
 797         if(!(wcp = fsp->wcp)) {
 798                 return;
 799         }
 800
 801         DO_PROFILE_DEC(writecache_allocated_write_caches);
 802         allocated_write_caches--;
 803
 804         SMB_ASSERT(wcp->data_size == 0);
 805
 806         SAFE_FREE(wcp->data);
 807         SAFE_FREE(fsp->wcp);
 808
 809         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 810 }
 811
 812 /****************************************************************************
 813  Setup the write cache structure.
 814 ****************************************************************************/
 815
 816 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 817 {
 818         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 819         write_cache *wcp;
 820
 821         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 822                 return False;
 823         }
 824
 825         if(alloc_size == 0 || fsp->wcp) {
 826                 return False;
 827         }
 828
 829         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 830                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 831                 return False;
 832         }
 833
 834         wcp->file_size = file_size;
 835         wcp->offset = 0;
 836         wcp->alloc_size = alloc_size;
 837         wcp->data_size = 0;
 838         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 839                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 840                         (unsigned int)wcp->alloc_size ));
 841                 SAFE_FREE(wcp);
 842                 return False;
 843         }
 844
 845         memset(wcp->data, '\0', wcp->alloc_size );
 846
 847         fsp->wcp = wcp;
 848         DO_PROFILE_INC(writecache_allocated_write_caches);
 849         allocated_write_caches++;
 850
 851         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 852                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
 853
 854         return True;
 855 }
 856
 857 /****************************************************************************
 858  Cope with a size change.
 859 ****************************************************************************/
 860
 861 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 862 {
 863         if(fsp->wcp) {
 864                 /* The cache *must* have been flushed before we do this. */
 865                 if (fsp->wcp->data_size != 0) {
 866                         char *msg;
 867                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 868                                  "on file %s with write cache size = %lu\n",
 869                                  fsp->fsp_name,
 870                                  (unsigned long)fsp->wcp->data_size) != -1) {
 871                                 smb_panic(msg);
 872                         } else {
 873                                 smb_panic("set_filelen_write_cache");
 874                         }
 875                 }
 876                 fsp->wcp->file_size = file_size;
 877         }
 878 }
 879
 880 /*******************************************************************
 881  Flush a write cache struct to disk.
 882 ********************************************************************/
 883
 884 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 885 {
 886         write_cache *wcp = fsp->wcp;
 887         size_t data_size;
 888         ssize_t ret;
 889
 890         if(!wcp || !wcp->data_size) {
 891                 return 0;
 892         }
 893
 894         data_size = wcp->data_size;
 895         wcp->data_size = 0;
 896
 897         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 898
 899         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 900                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 901
 902 #ifdef WITH_PROFILE
 903         if(data_size == wcp->alloc_size) {
 904                 DO_PROFILE_INC(writecache_num_perfect_writes);
 905         }
 906 #endif
 907
 908         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 909
 910         /*
 911          * Ensure file size if kept up to date if write extends file.
 912          */
 913
 914         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 915                 wcp->file_size = wcp->offset + ret;
 916         }
 917
 918         return ret;
 919 }
 920
 921 /*******************************************************************
 922 sync a file
 923 ********************************************************************/
 924
 925 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
 926 {
 927         if (fsp->fh->fd == -1)
 928                 return NT_STATUS_INVALID_HANDLE;
 929
 930         if (lp_strict_sync(SNUM(conn)) &&
 931             (lp_syncalways(SNUM(conn)) || write_through)) {
 932                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 933                 if (ret == -1) {
 934                         return map_nt_error_from_unix(errno);
 935                 }
 936                 ret = SMB_VFS_FSYNC(fsp);
 937                 if (ret == -1) {
 938                         return map_nt_error_from_unix(errno);
 939                 }
 940         }
 941         return NT_STATUS_OK;
 942 }
 943
 944 /************************************************************
 945  Perform a stat whether a valid fd or not.
 946 ************************************************************/
 947
 948 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 949 {
 950         if (fsp->fh->fd == -1) {
 951                 return SMB_VFS_STAT(fsp->conn, fsp->fsp_name, pst);
 952         } else {
 953                 return SMB_VFS_FSTAT(fsp, pst);
 954         }
 955 }